1. Field of the Invention
The present invention relates to a magnetic structure, for example, a magnetic head to be mounted on a magnetic recording/reproducing apparatus, such as a video cassette tape recorder or an audio tape recorder, and more particularly to a multi-channel magnetic head adaptable to a high density recording/reproducing operation in which data must be simultaneously recorded/reproduced to and from an array composed of a multiplicity of head chips.
2. Description of the Related Art
A magnetic recording apparatus, such as a digital VCR for recording video signals by a PCM (Pulse Code Modulation) method or a high grade VCR for recording high grade video signals, must record a considerably large quantity of signals as compared with a conventional household VCR or a digital audio tape recorder. Therefore, wide band signals as compared with the foregoing conventional apparatuses must be recorded/reproduced. Since a multi-track recording method is effective to record/reproduce the wide band signals, a multi-channel magnetic head has been suggested. In order to reduce the size and the weight of the magnetic recording apparatus and to enlarge the recording capacity, the track must be narrowed and the relative speed between the magnetic recording medium and the head must be decreased. However, the foregoing structure raises a problem in that a reproduction signal having a sufficient S/N ratio cannot easily be obtained. Therefore, a magnetic head comprising a multiplex-winding coil and a recording/reproducing combined type head has been suggested in order to obtain a reproduction signal having a sufficient S/N ratio even if the relative speed is not sufficient high.
The multi-channel magnetic head is categorized to a magnetic head comprising a single head chip of a plural-bulk type which is secured to the base thereof and a magnetic head having an arrangement that a multiplicity of thin-film head chips are formed on the same substrate. The latter thin-film type magnetic head exhibits an advantage in terms of facility of narrowing the track and improving the relative positional accuracy between the magnetic gaps. The multi-channel thin-film magnetic head has been disclosed in Japanese Patent Laid-Open No. 4-186511, Japanese Patent Laid-Open No. 4-188414, Japanese Patent Laid-Open No. 2-179910, Japanese Patent Laid-Open No. 62-31013, Japanese Patent Laid-Open No. 61-39914 and Japanese Patent Laid-Open No. 58-94120. The multi-channel magnetic head of the recording/reproducing combined type has been disclosed in Japanese Patent Laid-Open No. 2-94014.
The conventional multi-channel thin-film magnetic head is categorized to a type arranged as shown in FIG. 68A and comprising a magnetic head chip having a multiplicity of spiral-type coils and to a type arranged as shown in FIG. 68B and comprising a magnetic head chip having a helical coil. Referring to FIGS. 68A and 68B, reference numeral 1 represents a substrate, 25 represents a spiral coil, 26 represents a helical coil, and 31 represents a magnetic core. The magnetic head chip comprising the spiral coil exhibits an advantage that it can easily be manufactured and the insulation of the coil can easily be realized. However, the fact that the area is enlarged if the number of turns is increased for the purpose of obtaining a satisfactory reproduction signal output undesirably widens the intervals between the magnetic head chips at the time of integrating a multiplicity of the magnetic head chips, and therefore, there arises a problem in that the track cannot easily be narrowed.
The magnetic head chip having the helical coil shown in FIG. 68B enables narrowing of the track and increasing in the number of turns to be realized easily. However, limitations present in the size of the magnetic head inhibit to obtain a sufficiently large number of turns and therefore a problem is raised in that the S/N ratio of the reproduction signal is lowered. Further, the structure arranged in such a manner that the coil 26a and the magnetic core 31 are integrally formed by a lithography technology inhibits satisfactorily thickening the magnetic core 31 at the time of forming the coil 26. In this case, there arises a problem in that the recording/reproducing efficiency cannot easily be improved.
If the connection between the coil of the magnetic head chip and an external electric circuit is established by a conventional method in which the electrode pads disposed at both ends of each coil are bonded or connected by making use of connectors, the number of connections is greatly increased in a case of a multi-channel structure comprising tens to hundreds of tracks. In this case, there arises a problem that reliability deteriorates and connection cannot easily be established because the diameter of the connection cable cannot be reduced. What is worse, the size of the electrode pad sometimes limits the intervals between the magnetic head chips. Therefore, a problem rises in that the magnetic head chips cannot easily be disposed at intervals shorter than the size of the electrode pad.
The conventional multi-channel thin-film magnetic head encounters a problem in that a satisfactory tracking operation cannot be performed if the track width and the track angle have been changed due to expansion/contraction of the magnetic recording medium occurring due to heat.